In a typical cellular radio system, wireless user equipment units (UEs) communicate via a radio access network (RAN) to one or more core networks. The user equipment units (UEs) can be mobile stations such as mobile telephones (“cellular” telephones) and laptops with mobile termination, and thus can be, for example, portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with radio access network. Alternatively, the wireless user equipment units can be fixed wireless devices, e.g., fixed cellular devices/terminals which are part of a wireless local loop or the like.
The radio access network (RAN) covers a geographical area which is divided into cell areas, with each cell area being served by a base station. A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. Each cell is identified by a unique identity, which is broadcast in the cell. The base stations communicate over the air interface (e.g., radio frequencies) with the user equipment units (UE) within range of the base stations. In the radio access network, several base stations are typically connected (e.g., by landlines or microwave) to a radio network controller (RNC). The radio network controller, also sometimes termed a base station controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The radio network controllers are typically connected to one or more core networks. The core network has two service domains, with an RNC having an interface to both of these domains.
One example of a radio access network is the Universal Mobile Telecommunications (UMTS) Terrestrial Radio Access Network (UTRAN). The UMTS is a third generation system which in some respects builds upon the radio access technology known as Global System for Mobile communications (GSM) developed in Europe. UTRAN is essentially a radio access network providing wideband code division multiple access (WCDMA) to user equipment units (UEs). The Third Generation Partnership Project (3GPP) has undertaken to evolve further the UTRAN and GSM-based radio access network technologies.
As those skilled in the art appreciate, in WCDMA technology a common frequency band allows simultaneous communication between a user equipment unit (UE) and plural base stations. Signals occupying the common frequency band are discriminated at the receiving station through spread spectrum CDMA waveform properties based on the use of a high speed, pseudo-noise (PN) code. These high speed PN codes are used to modulate signals transmitted from the base stations and the user equipment units (UEs). Transmitter stations using different PN codes (or a PN code offset in time) produce signals that can be separately demodulated at a receiving station. The high speed PN modulation also allows the receiving station to advantageously generate a received signal from a single transmitting station by combining several distinct propagation paths of the transmitted signal. In CDMA, therefore, a user equipment unit (UE) need not switch frequency when handoff of a connection is made from one cell to another. As a result, a destination cell can support a connection to a user equipment unit (UE) at the same time the origination cell continues to service the connection. Since the user equipment unit (UE) is always communicating through at least one cell during handover, there is no disruption to the call. Hence, the term “soft handover.” In contrast to hard handover, soft handover is a “make-before-break” switching operation.
The Internet Engineering Task Force (IETF) has published several standards for supporting mobility in IP networks. All these standards focus on the version 6 of the Internet Protocol (IPv6). The standards are divided into two categories, those supporting macro-mobility and those supporting micro-mobility. Macro-mobility refers to mobility across several networks, while micro-mobility refers to mobility within a single and potentially large network. Macro-mobility protocols allow a mobile node attached to a foreign network to communicate with other hosts using its home (permanent) IPv6 address. The IETF's macro-mobility protocol is the Mobile IPv6 (MIPv6) protocol. See, e.g., D. Johnson et al, Mobility Support in IPv6, RFC 3775, June 2004.
Micro-mobility protocols aim to improve localized mobility by reducing the handover overheads. Fast Handover and Hierarchical MIPv6 (FMIPv6 and HMIPv6) are two micro-mobility protocols standardized by the IETF. See, respectively, e.g., R. Koodli, Fast Handovers for Mobile IPv6, RFC 4068, July 2005, and H. Soliman at al, Hierarchical Mobile IPv6 Mobility Management (HMIPv6), RFC 4140, August 2005.
Currently, IETF charters such as NETLMM (Network-based Localized Mobility Management) and MIPSHOP (Mobility for IP: Performance, Signaling, and Handoff Optimizations) are proposing new micro-mobility architectures for IPv6. See, respectively, e.g., Network-based Localized Mobility Management, http://www.ietf.org/html.charters/netlmm-charter.html; and Mobility for IP: Performance, Signaling and Handoff Optimization, http://www.ietforg/html.charters/mipshop-charter.html.
Existing solutions for IP mobility suffer significant drawbacks that make these solutions simply undeployable. As one drawback, the complexity of the proposed solutions render implementation on small mobile devices (such as cell phones and handhelds) unfeasible. In fact, manufactures of such devices never anticipated supporting the present solutions.
Another serious drawback is the delay on the deployment of IPv6. Consensus ten years ago was that that IPv6 was inevitable (due to the shortage of IPv4 addresses [mainly the class B addresses] caused by the exponential growth of the Internet). However, solutions devised in the meantime proved the contrary. CIDR (Classless Interdomain Routing) allows a block of class C addresses be grouped and advertised as a single prefix, while NAT (Network Address Translation) allows the use of unlimited private address spaces. As such, IPv4 networks remain growing and operating without the limits identified a decade ago.
Support for micro-mobility is a key issue in mobile networks since it speeds up the handover process, minimizing communication disruptions when a mobile node changes its network point of attachment.
What is needed, therefore, and an object of the present invention, is one or more of apparatus, methods, systems, and techniques for supporting micro-mobility in a telecommunications network without complexity or dependence upon IPv6.